Systems and methods for removing finely dispersed particulate matter from a fluid stream

ABSTRACT

Disclosed herein are systems for removing particulate matter from a fluid, comprising a particle functionalized by attachment of at least one activating group or amine functional group, wherein the modified particle complexes with the particulate matter within the fluid to form a removable complex therein. The particulate matter has preferably been contacted, complexed or reacted with a tethering agent. The system is particularly advantageous to removing particulate matter from a tailing solution.

RELATED PARAGRAPH

This application claims the benefit of U.S. Provisional Application Nos.61/028,717, filed on Feb. 14, 2008; 61/117,757, filed on Nov. 25, 2008;and 61/140,525 filed on Dec. 23, 2008. The entire teachings of the aboveapplications are incorporated herein by reference.

PARTIES TO A JOINT RESEARCH AGREEMENT

Soane Mining, LLC and Soane Energy, LLC are parties to a “joint researchagreement” as defined in 35 USC 103(c)(3).

FIELD OF THE APPLICATION

The application relates generally to particles useful for removingfinely dispersed particulate matter from fluid streams.

BACKGROUND

Fine materials generated from mining activities are often foundwell-dispersed in aqueous environments, such as wastewater. The finelydispersed materials may include such solids as various types of claymaterials, recoverable materials, fine sand and silt. Separating thesematerials from the aqueous environment can be difficult, as they tend toretain significant amounts of water, even when separated out, unlessspecial energy-intensive dewatering processes or long-term settlingpractices are employed.

An example of a high volume water consumption process is the processingof naturally occurring ores, such as coal and oil sands. Naturallyoccurring ores are heterogeneous mixtures of hydrophobic organicmolecules and solid inorganic matter. During the processing of suchores, colloidal particles, such as clay and mineral fines, are releasedinto the aqueous phase often due to the introduction of mechanical shearassociated with the hydrocarbon-extraction process. In addition tomechanical shear, alkali water is sometimes added during extraction,creating an environment more suitable for colloidal suspensions. Acommon method for disposal of the resulting “tailing” solutions, whichcontain fine colloidal suspensions of clay and minerals, water, sodiumhydroxide and small amounts of remaining hydrocarbon, is to store themin “tailings ponds”. These ponds take years to settle out thecontaminating fines, making the water unsuitable for recycling.

Certain industrial processes that use a large volume of water placestrains on the local water supply. For example, in the oil sandsextraction industry, flow rate decreases have been observed in thenearby rivers from which processing water is drawn. As a specificexample, water demands are a great concern in Athabasca, an oil sanddeposit located in northern Alberta Canada, near the Athabasca River.Oil sands from the Athabasca deposit are being mined and processed at arate of roughly 1,000 kilotonnes per day. The water demand to processthis amount of ore adds up to roughly 500 kdam³ per year, accounting for8% of the province's water usage. With the vast majority of the waterending up in tailings ponds, eventually the surrounding rivers will nolonger be able to sustain the industry's water demand. An effective andefficient method of recycling water in this industry is essential forits long-term viability.

In addition, certain industrial processes can create waste streams oflarge-particle inorganic solids. Using the oil sands example, inorganicsolids such as quartz remain after the extraction of hydrocarbon fromthe oil sands ore. Since the ore that is processed only contains about8-12% desirable hydrocarbon, a large amount of large-particle inorganicmaterial remains after hydrocarbon extraction. This residue is typicallyremoved in initial separation phases of processing due to its size,insolubility and ease of sequestering. Disposal or storage of this wastematerial has become a problem for the oil sands industry, again due tothe vast volume of many industrial processes. Attempts have been made touse this large coarse solid as a flocculant ballast for the finecolloidal suspension in the tailings ponds; however, aggregation has notbeen sustainably observed. It would be advantageous to modify thismaterial so that it could be useful in-situ for wastewater treatmentpurposes.

A typical approach to consolidating fine materials dispersed in waterinvolves the use of coagulants or flocculants. This technology works bylinking together the dispersed particles by use of multivalent metalsalts (such as calcium salts, aluminum compounds or the like) or highmolecular weight polymers such as partially hydrolyzed polyacrylamides.With the use of these agents, there is an overall size increase in thesuspended particle mass; moreover, their surface charges areneutralized, so that the particles are destabilized. The overall resultis an accelerated sedimentation of the treated particles. Following thetreatment, though, a significant amount of water remains trapped withthe sedimented particles. These technologies typically do not releaseenough water from the sedimented material that the material becomesmechanically stable. In addition, the substances used forflocculation/coagulation may not be cost-effective, especially whenlarge volumes of wastewater require treatment, in that they requirelarge volumes of flocculant and/or coagulant. While ballastedflocculation systems have also been described, these systems areinefficient in sufficiently removing many types of fine particles, suchas those fine particles that are produced in an oil sands mining.

Particular needs exist in the oil sands industry for removing suspendedparticles from fluid solutions. Tailings flowing directly fromprocessing oil sands (termed “whole tailings”) can contain fine clayparticles (termed “clay fines”) suspended in an alkaline water solution,along with suspended sand and other particulate matter. The wholetailings can be separated into two fluid streams by processes such ascycloning, where one fluid stream (called the underflow) contains sand,and the other fluid stream (called the overflow) contains the suspendedfine clay particles. The overflow from cycloning that contains the fineclay particles is termed fine tailings. Fine tailings can be directed tolarge man-made tailings ponds to allow the clay particles to settle outgradually via gravity. The settling process can take many years.Tailings ponds typically have four layers, including a bed of settledsand, an overlying thick liquid layer called “mature fine tailings,” aliquid layer bearing suspended fines, and a supernatant layer ofclarified water. This watery top layer, chilled by exposure to theambient air temperature, can be reused for oil sands processing, but itmust be heated up to the processing temperature of approximately between50°-80° C. before it can be used.

There remains an overall need in the art, therefore, for a treatmentsystem that removes suspended particles from a fluid solution quickly,cheaply, and with high efficacy. It is also desirable that the treatmentsystem yield a recovered (or recoverable) solid material that retainsminimal water, so that it can be readily processed into a substance thatis mechanically stable, potentially capable of bearing weight orsupporting vehicular traffic, i.e., “trafficable.” It is furtherdesirable that the treatment system yield a clarified water that can bereadily recycled for further industrial purposes.

As applied to the oil industry, it is desirable that the whole tailingsbe processed before being directed to the tailings ponds so that thewater is separated from the suspended solids. If this separation isperformed soon after oil sands processing, the recovered water willstill be hot, so that there can be conservation of energy needed to heatthe recycled water to the processing temperature. Furthermore,processing the whole tailings to recover water and solids can decreasethe amount of waste materials that must be stored in facilities liketailings ponds.

An additional need in the art pertains to the management of existingtailings ponds. In their present form, they are environmentalliabilities that may require extensive clean-up efforts in the future.It is desirable to prevent their expansion. It is further desirable toimprove their existing state, so that their contents settle moreefficiently and completely. A more thorough and rapid separation ofsolid material from liquid solution in the tailings pond could allowretrieval of recyclable water and compactable waste material, with anoverall reduction of the footprint that they occupy.

SUMMARY

Disclosed herein are systems for removing particulate matter from afluid, comprising a particle functionalized by attachment of at leastone amine functional group, wherein the modified particle complexes withthe particulate matter within the fluid to form a removable complextherein. In embodiments, the fluid can be a tailing solution. Inembodiments, the particulate matter can be quartz or clay fines. Inembodiments, the removable complex is more dense than the fluid. Inembodiments, the removable complex is less dense than the fluid.

Also disclosed herein are methods for removing particulate matter from afluid, comprising providing a modified particle comprising a particlefunctionalized by attachment of at least one amine functional group,dispersing the modified particle within the fluid so that it contactsthe particulate matter to form a removable complex in the fluid, andremoving the removable complex from the fluid. In embodiments, the fluidcan be a tailing solution. In embodiments, the particulate matter can bequartz or clay fines. In embodiments, the removable complex can beremoved by filtration. In embodiments, the removable complex can beremoved by centrifugation, gravitational settling and/or skimming.

Disclosed herein are embodiments of systems for removing particulatematter from a fluid, comprising an activating material capable of beingaffixed to the particulate matter to form an activated particle, ananchor particle, and a tethering material capable of being affixed tothe anchor particle, wherein the tethering material attaches the anchorparticle and the activated particle to form a removable complex in thefluid. In embodiments, the anchor particle can comprise sand. Inembodiments, the tethering material can be selected from the groupconsisting of chitosan, lupamin, BPEI, and PDAC. The activated particlecan be a particle functionalized by attachment of at least one aminefunctional group, as described above.

Disclosed herein are embodiments of methods of removing particulatematter from a fluid, comprising providing an activating material capableof being affixed to the particulate matter, affixing the activatingmaterial to the particulate matter to form an activated particle,providing an anchor particle and providing a tethering material capableof being affixed to the anchor particle, and attaching the tetheringmaterial to the anchor particle and the activated particle to form aremovable complex in the fluid that comprises the particulate matter.Practices of the disclosed methods can comprise removing the removablecomplex from the fluid. In certain practices, the removable complex canbe removed by filtration, centrifugation and/or gravitational settling.In certain practices, the anchor particle can comprise sand. In certainpractices, the tethering material can be selected from the groupconsisting of chitosan, lupamin, BPEI, and PDAC. In certain practices,the particulate matter can comprise quartz and/or clay fines. Disclosedherein are also embodiments of products produced or producible by theaforesaid methods. Further disclosed herein are waste treatment pondscharacterized by a beach or pond floor obtained from or obtainable bythe aforesaid methods.

DETAILED DESCRIPTION

Disclosed herein are systems and methods for enhancing the settlementrate of dispersed fine materials by incorporating them within a coarserparticulate matrix, so that solids can be removed from aqueoussuspension as a material having mechanical stability. The systems andmethods disclosed herein involve three components: activating the fineparticles, tethering them to anchor particles, and sedimenting the fineparticle-anchor particle complex.

1. Activation

As used herein, the term “activation” refers to the interaction of anactivating material, such as a polymer, with suspended particles in aliquid medium, such as an aqueous solution. In embodiments, highmolecular weight polymers can be introduced into the particulatedispersion, so that these polymers interact, or complex, with fineparticles. The polymer-particle complexes interact with other similarcomplexes, or with other particles, and form agglomerates.

This “activation” step can function as a pretreatment to prepare thesurface of the fine particles for further interactions in the subsequentphases of the disclosed system and methods. For example, the activationstep can prepare the surface of the fine particles to interact withother polymers that have been rationally designed to interact therewithin an optional, subsequent “tethering” step, as described below. Not tobe bound by theory, it is believed that when the fine particles arecoated by an activating material such as a polymer, these coatedmaterials can adopt some of the surface properties of the polymer orother coating. This altered surface character in itself can beadvantageous for sedimentation, consolidation and/or dewatering.

Particles suitable for modification, or activation, can include organicor inorganic particles, or mixtures thereof. Inorganic particles caninclude one or more materials such as calcium carbonate, dolomite,calcium sulfate, kaolin, talc, titanium dioxide, sand, diatomaceousearth, aluminum hydroxide, silica, other metal oxides and the like.Sand, such as sand recovered from the mining process itself, ispreferred. Organic particles can include one or more materials such asstarch, modified starch, polymeric spheres (both solid and hollow), andthe like. Particle sizes can range from a few nanometers to few hundredmicrons. In certain embodiments, macroscopic particles in the millimeterrange may be suitable.

In embodiments, a particle, such as an amine-modified particle, maycomprise materials such as lignocellulosic material, cellulosicmaterial, vitreous material, cementitious material, carbonaceousmaterial, plastics, elastomeric materials, and the like. In embodiments,cellulosic and lignocellulosic materials may include wood materials suchas wood flakes, wood fibers, wood waste material, wood powder, lignins,or fibers from woody plants.

Examples of inorganic particles include clays such as attapulgite andbentonite. In embodiments, the inorganic compounds can be vitreousmaterials, such as ceramic particles, glass, fly ash and the like. Theparticles may be solid or may be partially or completely hollow. Forexample, glass or ceramic microspheres may be used as particles.Vitreous materials such as glass or ceramic may also be formed as fibersto be used as particles. Cementitious materials may include gypsum,Portland cement, blast furnace cement, alumina cement, silica cement,and the like. Carbonaceous materials may include carbon black, graphite,carbon fibers, carbon microparticles, and carbon nanoparticles, forexample carbon nanotubes.

In embodiments, plastic materials may be used as particles. Boththermoset and thermoplastic resins may be used to form plasticparticles. Plastic particles may be shaped as solid bodies, hollowbodies or fibers, or any other suitable shape. Plastic particles can beformed from a variety of polymers. A polymer useful as a plasticparticle may be a homopolymer or a copolymer. Copolymers can includeblock copolymers, graft copolymers, and interpolymers. In embodiments,suitable plastics may include, for example, addition polymers (e.g.,polymers of ethylenically unsaturated monomers), polyesters,polyurethanes, aramid resins, acetal resins, formaldehyde resins, andthe like. Addition polymers can include, for example, polyolefins,polystyrene, and vinyl polymers. Polyolefins can include, inembodiments, polymers prepared from C₂-C₁₀ olefin monomers, e.g.,ethylene, propylene, butylene, dicyclopentadiene, and the like. Inembodiments, poly(vinyl chloride) polymers, acrylonitrile polymers, andthe like can be used. In embodiments, useful polymers for the formationof particles may be formed by condensation reaction of a polyhydriccompound (e.g., an alkylene glycol, a polyether alcohol, or the like)with one or more polycarboxylic acids. Polyethylene terephthalate is anexample of a suitable polyester resin. Polyurethane resins can include,e.g., polyether polyurethanes and polyester polyurethanes. Plastics mayalso be obtained for these uses from waste plastic, such aspost-consumer waste including plastic bags, containers, bottles made ofhigh density polyethylene, polyethylene grocery store bags, and thelike.

In embodiments, plastic particles can be formed as expandable polymericpellets. Such pellets may have any geometry useful for the specificapplication, whether spherical, cylindrical, ovoid, or irregular.Expandable pellets may be pre-expanded before using them. Pre-expansioncan take place by heating the pellets to a temperature above theirsoftening point until they deform and foam to produce a loosecomposition having a specific density and bulk. After pre-expansion, theparticles may be molded into a particular shape and size. For example,they may be heated with steam to cause them to fuse together into alightweight cellular material with a size and shape conforming to themold cavity. Expanded pellets may be 2-4 times larger than unexpandedpellets. As examples, expandable polymeric pellets may be formed frompolystyrenes and polyolefins. Expandable pellets are available in avariety of unexpanded particle sizes. Pellet sizes, measured along thepellet's longest axis, on a weight average basis, can range from about0.1 to 6 mm.

In embodiments, the expandable pellets may be formed by polymerizing thepellet material in an aqueous suspension in the presence of one or moreexpanding agents, or by adding the expanding agent to an aqueoussuspension of finely subdivided particles of the material. An expandingagent, also called a “blowing agent,” is a gas or liquid that does notdissolve the expandable polymer and which boils below the softeningpoint of the polymer. Blowing agents can include lower alkanes andhalogenated lower alkanes, e.g., propane, butane, pentane, cyclopentane,hexane, cyclohexane, dichlorodifluoromethane, andtrifluorochloromethane, and the like. Depending on the amount of blowingagent used and the technique for expansion, a range of expansioncapabilities exist for any specific unexpanded pellet system. Theexpansion capability relates to how much a pellet can expand when heatedto its expansion temperature. In embodiments, elastomeric materials canbe used as particles. Particles of natural or synthetic rubber can beused, for example.

In embodiments, the particle can be substantially larger than the fineparticulates it is separating out from the process stream. For example,for the removal of particulate matter with approximate diameters lessthan 50 microns, particles may be selected for modification havinglarger dimensions. In other embodiments, the particle can besubstantially smaller than the particulate matter it is separating outof the process stream, with a number of such particles interacting inorder to complex with the much larger particulate matter. Particles mayalso be selected for modification that have shapes adapted for easiersettling when compared to the target particulate matter: sphericalparticles, for example, may advantageously be used to remove flake-typeparticulate matter. In other embodiments, dense particles may beselected for modification, so that they settle rapidly when complexedwith the fine particulate matter in the process stream. In yet otherembodiments, extremely buoyant particles may be selected formodification, so that they rise to the fluid surface after complexingwith the fine particulate matter, allowing the complexes to be removedvia a skimming process rather than a settling-out process. Inembodiments where the modified particles are used to form a filter, asin a filter cake, the particles selected for modification can be chosenfor their low packing density or porosity. Advantageously, particles canbe selected that are indigenous to a particular geographical regionwhere the particulate removal process would take place. For example,sand can be used as the particle to be modified for removing particulatematter from the waste stream (tailings) of oil sands mining.

It is envisioned that the complexes formed from the modified particlesand the particulate matter can be recovered and used for otherapplications. For example, when sand is used as the modified particleand it captures fine clay in tailings, the sand/clay combination can beused for road construction in the vicinity of the mining sites, due tothe less compactable nature of the complexes compared to other locallyavailable materials.

The “activation” step may be performed using flocculants or otherpolymeric substances. Preferably, the polymers or flocculants can becharged, including anionic or cationic polymers. In embodiments, anionicpolymers can be used, including, for example partially hydrolyzedpolyacrylamide, polyacrylic acid, polymethacrylic acid, sulfonatedpolystyrene, and the like. Suitable polycations include:polydiallyldimethylammonium chloride, branched or linearpolyethyleneimine, polyvinylamine, and the like. Nonionic polymerssuitable for hydrogen bonding interactions can include polyethyleneoxide, polypropylene oxide, polyhydroxyethylacrylate,polyhydroxyethylmethacrylate, and the like. Flocculants such as thosesold under the trademark Magnafloc® by Ciba Specialty Chemicals can beused.

The activated particle can also be an amine functionalized or modifiedparticle. As used herein, the term “modified particle” can include anyparticle that has been modified by the attachment of one or more aminefunctional groups as described herein. The functional group on thesurface of the particle can be from modification using a multifunctionalcoupling agent or a polymer. The multifunctional coupling agent can bean amino silane coupling agent as an example. These molecules can bondto a particle surface (e.g., metal oxide surface) and then present theiramine group for interaction with the particulate matter. In the case ofa polymer, the polymer on the surface of the particles can be covalentlybound to the surface or interact with the surface of the particle and/orfiber using any number of other forces such as electrostatic,hydrophobic, or hydrogen bonding interactions. In the case that thepolymer is covalently bound to the surface, a multifunctional couplingagent can be used such as a silane coupling agent. Suitable couplingagents include isocyano silanes and epoxy silanes as examples. Apolyamine can then react with an isocyano silane or epoxy silane forexample. Polyamines include polyallyl amine, polyvinyl amine, chitosan,and polyethylenimine.

In embodiments, polyamines (polymers containing primary, secondary,tertiary, and/or quartenary amines) can also self-assemble onto thesurface of the particles or fibers to functionalize them without theneed of a coupling agent. For example, polyamines can self-assemble ontothe surface of the particles through electrostatic interactions. Theycan also be precipitated onto the surface in the case of chitosan forexample. Since chitosan is soluble in acidic aqueous conditions, it canbe precipitated onto the surface of particles by suspending theparticles in a chitosan solution and then raising the solution pH.

In embodiments, the amines or a majority of amines are charged. Somepolyamines, such as quartenary amines are fully charged regardless ofthe pH. Other amines can be charged or uncharged depending on theenvironment. The polyamines can be charged after addition onto theparticles by treating them with an acid solution to protonate theamines. In embodiments, the acid solution can be non-aqueous to preventthe polyamine from going back into solution in the case where it is notcovalently attached to the particle.

The polymers and particles can complex via forming one or more ionicbonds, covalent bonds, hydrogen bonding and combinations thereof, forexample. Ionic complexing is preferred.

To obtain activated fine materials, the activator could be introducedinto a liquid medium through several different means. For example, alarge mixing tank could be used to mix an activating material withtailings from oil sands processing bearing fine particulate materials.Alternatively, the activating material can be added along a transportpipeline and mixed, for example, by a static mixer or series of baffles.Activated particles are produced that can be treated with one or moresubsequent steps of tethering and anchor-separation.

The particles that can be activated are generally fine particles thatare resistant to sedimentation. Examples of particles that can befiltered in accordance with the invention include metals, sand,inorganic, or organic particles. The methods and products of theinvention are particularly useful to isolate particles generated frommining operations, such as oil sands processing or other mineralretrieval operations or other bitumen associated solids. The particlesare generally fine particles, such as particles having a mass meandiameter of less than 50 microns or particle fraction that remains withthe filtrate following a filtration with, for example, a 325 meshfilter. The particles to be removed in the processes described hereinare also referred to as “fines.”

2. Tethering

As used herein, the term “tethering” refers to an interaction between anactivated fine particle and an anchor particle (as described below) sothat the activated fine particles become tethered, linked or otherwiseattached to the anchor particle. When attached to activated fineparticles via tethering, the anchor particles enhance the rate andcompleteness of sedimentation or removal of the fine particles.

In accordance with these systems and methods, the tethering materialacts as a complexing agent to affix the activated particles to an anchormaterial. In embodiments, sand can be used as an anchor material, as maya number of other substances, as set forth in more detail below. Inembodiments, a tethering material can be any type of material thatinteracts strongly with the activating material and that is connectableto an anchor particle.

As used herein, the term “anchor particle” refers to a particle whichfacilitates the separation of fine particles. Generally, anchorparticles have a density that is greater than the liquid process stream.For example, anchor particles that have a density of greater than 1.3g/cc can be used. Additionally or alternatively, the density of theanchor particles can be greater than the density of the fine particlesor activated particles. Alternatively, the density is less than thedispersal medium, or density of the liquid or aqueous stream.Alternatively, the anchor particles are simply larger than particles. Adifference in density or particle size facilitates separating the solidsfrom the medium.

For example, for the removal of particulate matter with an approximatemass mean diameter less than 50 microns, anchor particles may beselected having larger dimensions, e.g., a mass mean diameter of greaterthan 70 microns. An anchor particle for a given system can have a shapeadapted for easier settling when compared to the target particulatematter: spherical particles, for example, may advantageously be used asanchor particles to remove particles with a flake or needle morphology.In other embodiments, increasing the density of the anchor particles maylead to more rapid settlement. Alternatively, less dense anchors mayprovide a means to float the fine particles, using a process to skim thesurface for removal. In this embodiment, one may choose anchor particleshaving a density of less than about 0.5 g/cc to remove fine particlesfrom an aqueous process stream.

Advantageously, anchor particles can be selected that are indigenous toa particular geographical region where the particulate removal processwould take place. For example, sand can be used as the anchor particlefor use in removing fine particulate matter from the waste stream(tailings) of oil sands mining.

Suitable anchor particles can be formed from organic or inorganicmaterials, or any mixture thereof. Anchor particle sizes (as measured asa mass mean diameter) can have a size up to few hundred microns,preferably greater than about 70 microns. In certain embodiments,macroscopic anchor particles up to and greater than about 1 mm may besuitable. Recycled materials or waste, particularly recycled materialsand waste having a mechanical strength and durability suitable toproduce a product useful in building roads and the like are particularlyadvantageous.

As an example of a tethering material used with an anchor particle inaccordance with these systems and methods, chitosan can be precipitatedonto sand particles, for example, via pH-switching behavior. Thechitosan can have affinity for anionic systems that have been used toactivate fine particles. In one example, partially hydrolyzedpolyacrylamide polymers can be used to activate particles, resulting ina particle with anionic charge properties. The cationic charge of thechitosans will attract the anionic charge of the activated particles, toattach the sand particles to the activated fine particles.

In embodiments, various interactions such as electrostatic, hydrogenbonding or hydrophobic behavior can be used to affix an activatedparticle or particle complex to a tethering material complexed with ananchor particle. In the foregoing example, electrostatic interactionscan govern the assembly of the activated fine particle complexes bearingthe anionic partially-hydrolyzed polyacrylamide polymer and the cationicsand particles complexed with the chitosan tethering material.

In embodiments, polymers such as linear or branched polyethyleneiminecan be used as tethering materials. It would be understood that otheranionic or cationic polymers could be used as tethering agents, forexample polydiallyldimethylammonium chloride. The efficacy of atethering material, however, can depend on the activating material. Ahigh affinity between the tethering material and the activating materialcan lead to a strong and/or rapid interaction there between.

A suitable choice for tether material is one that can remain bound tothe anchor surface, but can impart surface properties that arebeneficial to a strong complex formation with the activator polymer. Forexample, a polyanionic activator can be matched with a polycationictether material or a polycationic activator can be matched with apolyanionic tether material. In hydrogen bonding terms, a hydrogen bonddonor should be used in conjunction with a hydrogen bond acceptor. Inembodiments, the tether material can be complimentary to the chosenactivator, and both materials can possess a strong affinity to theirrespective deposition surfaces while retaining this surface property.

In other embodiments, cationic-anionic interactions can be arrangedbetween activated fine particles and tether-bearing anchor particles.The activator may be a cationic or an anionic material, as long as ithas an affinity for the fine particles to which it attaches. Thecomplementary tethering material can be selected to have affinity forthe specific anchor particles being used in the system. In otherembodiments, hydrophobic interactions can be employed in theactivation-tethering system.

The anchor particle material is preferably added in an amount whichpermits a flowable slurry. For example, the particle material can beadded in an amount greater than 1 gram/liter but less than the amountwhich results in a non-flowable sludge, amounts between about 1 to about10 grams/liter, preferably 2 to 6 g/l are often suitable. In someembodiments, it may be desirable to maintain the concentration of theanchor particles to 20 g/l of higher. The anchor particles may be fresh(unused) material, recycled, cleaned ballast, or recycled, uncleanedballast.

3. Settling

It is envisioned that the complexes formed from the anchor particles andthe activated particulate matter can be recovered and used for otherapplications. For example, when sand is used as the modified particleand it captures fine clay in tailings, the sand/clay combination can beused for road construction in the vicinity of the mining sites, due tothe less compactable nature of the complexes compared to other locallyavailable materials.

In embodiments, the interactions between the activated fine particlesand the tether-bearing anchor particles can enhance the mechanicalproperties of the complex that they form. For example, an activated fineparticle or collection thereof can be durably bound to one or moretether-bearing anchor particles, so that they do not segregate or movefrom the position that they take on the particles. This property of thecomplex can make it mechanically more stable.

Increased compatibility of the activated fine materials with a denser(anchor) matrix modified with the appropriate tether polymer can lead tofurther mechanical stability of the resulting composite material. Thisbecomes quite important when dealing with tailings resulting frommining. This composite material can then be further utilized within theproject for road building, dyke construction, or even land reclamation,rather than simply left in a pond to settle at a much slower rate.

A variety of techniques are available for removing theactivated-tethered-anchored complexes from the fluid stream. Forexample, the tether-bearing anchor particles can be mixed into a streamcarrying activated fine particles, and the complexes can then separatedvia a settling process such as gravity or centrifugation. In anothermethod, the process stream carrying the activated fine particles couldflow through a bed or filter cake of the tether-bearing anchorparticles. In any of these methods, the modified particles interact withthe fine particulates and pull them out of suspension so that laterseparation removes both modified particles and fine particulates.

As would be appreciated by artisans of ordinary skill, a variety ofseparation processes could be used to remove the complexes of modifiedparticles and fine particulates. For example, if the anchor particleshad magnetic properties, the complexes formed by the interaction oftether-bearing anchor particles and activated fine particulates could beseparated using a magnetic field. As another example, if thetether-bearing anchor particles were prepared so that they wereelectrically conductive, the complexes formed by the interaction oftether-bearing anchor particles and activated fine particulates could beseparated using an electric field.

As would be further appreciated by those of ordinary skill,tether-bearing anchor particles could be designed to complex with aspecific type of activated particulate matter. The systems and methodsdisclosed herein could be used for complexing with organic wasteparticles, for example. Other activation-tethering-anchoring systems maybe envisioned for removal of suspended particulate matter in fluidstreams, including gaseous streams.

4. Applications

a. In-Line Tailings Processing

Extraction of bitumen from oil sands can involve the use of hot waterwith a caustic agent applied to the mined oil sands ore. During thisprocess, clay particulate matter bound up in the oil sands ore can beexfoliated, producing fine, positively charged clay particles (“fines”)that remain suspended in the effluent fluid stream. The effluent fluidstream can be directed to a mechanical separator such as a cyclone thatcan separate the fluid stream into two components, an overflow fluidcomprising fine tails that contains the fine (<approximately 50 micron)clay particles, and an underflow fluid stream that contains coarsetails, mainly sand, with a small amount of fine clay particles.

In embodiments, the systems and methods disclosed herein can treat eachfluid stream (including, but not limited to, effluent fluid streams frombitumen extraction methods), an overflow fluid and/or an underflowfluid. An activating agent, such as a polyanion as described above, canpreferably be introduced into the overflow fluid stream, resulting in aflocculation of the fine particles therein, often forming a soft, spongymass. The underflow fluid can be used for the preparation oftether-bearing anchor particles. However, it will be clear that othersources for anchor particles (e.g., sand) can also be used. The sandwithin the underflow fluid can act as an “anchor particle,” as describedabove. A cationic tethering agent, as described above, can be introducedinto the underflow fluid so that it self-assembles onto the surface ofthe anchor particles, creating a plurality of tether-bearing anchorparticles.

Following this treatment to each fluid stream, the two fluid streams canbe re-mixed in a batch, semi-batch or continuous fashion. Thetether-bearing anchor particles can interact, preferablyelectrostatically, with the activated, preferably flocculating, fineclay particles, forming large agglomerations of solid material that canbe readily removed from or settled in the resulting fluid mixture.

In embodiments, the aforesaid systems and methods are amenable toincorporation within existing tailings separation systems. For example,a treatment process can be added in-line to each of the separate flowsfrom the overflow and underflow fluids; treated fluids then re-convergeto form a single fluid path from which the resulting agglomerations canbe removed. Removal of the agglomerations can take place, for example,by filtration, centrifugation, or other type of mechanical separation.

In one embodiment, the fluid path containing the agglomerated solids canbe subsequently treated by a conveyor belt system, analogous to thosesystems used in the papermaking industry. In an exemplary conveyor beltsystem, the mixture of fluids and agglomerated solids resulting from theelectrostatic interactions described above can enter the system via aheadbox. A moving belt containing a mechanical separator can movethrough the headbox, or the contents of the headbox are dispensed ontothe moving belt, so that the wet agglomerates are dispersed along themoving belt. One type of mechanical separator can be a filter with apore size smaller than the average size of the agglomerated particles.The size of the agglomerated particles can vary, depending upon the sizeof the constituent anchor particles (i.e., sand). For example, forsystems where the sand component has a size between 50/70 mesh, an 80mesh filter can be used. Other adaptations can be envisioned by artisanshaving ordinary skill in the art. Agglomerated particles can betransported on the moving belt and further dewatered. Water removed fromthe agglomerated particles and residual water from the headbox fromwhich agglomerates have been removed can be collected in whole or inpart within the system and optionally recycled for use in subsequent oilsands processing.

In embodiments, the filtration mechanism can be an integral part of themoving belt. In such embodiments, the captured agglomerates can bephysically removed from the moving belt so that the filter can becleaned and regenerated for further activity. In other embodiments, thefiltration mechanism can be removable from the moving belt. In suchembodiments, the spent filter can be removed from the belt and a newfilter can be applied. In such embodiments, the spent filter canoptionally serve as a container for the agglomerated particles that havebeen removed.

Advantageously, as the agglomerated particles are arrayed along themoving belt, they can be dewatered and/or dried. These processes can beperformed, for example, using heat, air currents, or vacuums.Agglomerates that have been dewatered and dried can be formed as solidmasses, suitable for landfill, construction purposes, or the like.

Desirably, the in-line tailings processing described above is optimizedto capitalize upon the robustness and efficiency of the electrostaticinteraction between the activated tailings and the tether-bearing anchorparticles. Advantageously, the water is quickly removed from the freshtailings during the in-line tailings processing, to minimize heatlosses. Recycling this hot water saves energy: water that is already hotdoes not require as much heating to get it to an operational processingtemperature, while recycling cold water, such as would be found intailings ponds, requires a substantial amount of heating and resultantenergy use.

b. Treatment Ponds

The systems and methods disclosed herein can be used for treatment oftailings at a facility remote from the oil sands production facility orin a pond. Similar principles are involved: the fluid stream bearing thefine tailings can be treated with an anionic activating agent,preferably initiating flocculation. A tether-bearing anchor particlesystem can then be introduced into the activated tailings stream, or theactivated tailings stream can be introduced into a tether-bearing anchorparticle system. In embodiments, a tailings stream containing fines canbe treated with an activating agent, as described above, and applied toa stationary or moving bed of tether-bearing anchor particles. Forexample, a stationary bed of tether-bearing anchor particles can bearranged as a flat bed over which the activated tailings stream ispoured. The tether-bearing anchor particles can be within a container orhousing, so that they can act as a filter to trap the activated tailingspassing through it. On a larger scale, the tether-bearing anchorparticles can be disposed on a large surface, such as a flat or inclinedsurface (e.g., a beach), so that the activated tailings can flow overand through it, e.g. directionally toward a pond.

As an example, sand particles retrieved from the underflow fluid streamcan be used as the anchor particles to which a cationic tether isattached. A mass of these tether-bearing anchor particles can bearranged to create a surface of a desired thickness, forming an“artificial beach” to which or across which the activated tailings canbe applied. As would be appreciated by those of ordinary skill in theart, the application of the activated tailings to the tether-bearinganchor particles can be performed by spraying, pouring, pumping,layering, flowing, or otherwise bringing the fluid bearing the activatedtailings into contact with the tether-bearing anchor particles. Theactivated tailings are then associated with the tether-bearing anchorparticles while the remainder of the fluid flows across the surface andinto a collection pond or container.

c. Tailings Pond Remediation

In embodiments, an adaptation of the activator-tether-anchor systemsdisclosed herein can be applied to the remediation of existing tailingsponds. Tailings ponds comprise four layers of materials, reflecting thegravity-induced settlement of fresh tailings after long residenceperiods in the pond. The top layer in the tailings pond comprisesclarified water. The next layer is a fluid suspension of fine clayparticles like fine tailings. The third layer, called “mature finetailings (MFTs),” is a stable suspension of fluid fine tailings that hasundergone self-weight consolidation/dewatering to a density of about 30to 45 wt % solids content over a period of about 2 or 3 years afterdeposition and that lacks sufficient strength to form a trafficablesurface. The rate of consolidation for MFTs is substantially reducedafter the initial self-weight consolidation period, and the suspensionacts like a viscous fluid containing suspended fine clay particles thathave not yet settled out. The bottom layer is formed predominately fromsand that has settled by gravity.

Desirably, the mature fine tailings (MFTs) can be treated to separatethe water that they contain from the fine clay particles suspendedtherein. If the MFTs can be treated, the resultant clarified water canbe drawn off and the solid material can be reclaimed. This could reducethe overall size of the tailings ponds, or prevent them from growinglarger as fresh untreated tailings are added.

In embodiments, the systems and methods disclosed herein can be adaptedto treat MFTs, such as are contained in tailings ponds. These systemsand methods thus present an opportunity for treating the tailings pondsoverall. In an embodiment, an activating agent, for example, one of theanionic polymers disclosed herein can be added to a pond, or MFT layerwithin a tailings pond, such as by injection with optional stirring oragitation. Tether-bearing anchor particles can then be added to the pondor layer containing the activated MFTs. For example, the tether-bearinganchor particles can be added to the pond from above, so that theydescend through the activated MFT layer. As the activated MFT layer isexposed to the tether-bearing anchor particles, the flocculated finescan adhere to the anchor particles and be pulled down to the bottom ofthe pond by gravity, leaving behind clarified water. The tailings pondcan thus be separated into two components, a top layer of clarifiedwater, and a bottom layer of congealed solid material. The top layer ofclarified water can then be recycled for use, for example in further oilsands processing. The bottom layer of solids can be retrieved, dewateredand used for construction purposes, landfill, and the like.

d. Treating Waste or Process Streams with Amine Modified Particles

Particles modified in accordance with these systems and methods may beadded to fluid streams to complex with the particulate matter suspendedtherein so that the complex can be removed from the fluid. Inembodiments, the modified particles and the particulate matter mayinteract through electrostatic, hydrophobic, covalent or any other typeof interaction whereby the modified particles and the particulate matterform complexes that are able to be separated from the fluid stream. Themodified particles can be introduced to the process or waste streamusing a variety of techniques so that they complex with the particulatematter to form a removable complex. A variety of techniques are alsoavailable for removing the complexes from the fluid stream. For example,the modified particles can be mixed into the stream and then separatedvia a settling process such as gravity or centrifugation. If buoyant orlow-density modified particles are used, they can be mixed with thestream and then separated by skimming them off the surface. In anothermethod, the process stream could flow through a bed or filter cake ofthe modified particles. In any of these methods, the modified particlesinteract with the fine particulates and pull them out of suspension sothat later separation removes both modified particles and fineparticulates.

As would be appreciated by artisans of ordinary skill, a variety ofseparation processes could be used to remove the complexes of modifiedparticles and fine particulates. For example, if the modified particleswere modified so as to be magnetic, the complexes of modified particlesand fine particulates could be separated using a magnetic field. Asanother example, of the modified particles were modified so as to beelectrically conductive, the complexes of modified particles and fineparticulates could be separated using an electric field.

EXAMPLES Materials

The Following Chemicals Were Used in the Examples Below:

-   Washed Sea Sand, 50+70 Mesh-   Sigma Aldrich-   St. Louis, Mo.-   Chitosan CG 800-   Primex-   Siglufjodur, Iceland-   Branched Polyethyleneimine (BPEI) (50% w/v)-   Sigma Aldrich-   St. Louis, Mo.-   Polyvinyl Amine-Lupamin 1595, Lupamin 9095-   BASF-   Ludwigshafen, Germany-   Poly(diallyldimethylammonium chloride) (pDAC) (20% w/v)-   Sigma Aldrich-   St. Louis, Mo.-   FD&C Blue #1-   Sigma Aldrich-   St. Louis, Mo.-   Hydrochloric Acid-   Sigma Aldrich-   St. Louis, Mo.    Tailings Solution from a Low-Grade Tar Sand-   Dicalite, Diatomaceous Earth-   Grefco Minerals, Inc.-   Burney, Calif.-   3-Isocyanatopropyltriethoxysilane-   Gelest-   Morrisville, Pa.-   Sodium Hydroxide-   Sigma Aldrich-   St. Louis, Mo.-   Isopropyl Alcohol (IPA)-   Sigma Aldrich-   St. Louis, Mo.

Example 1 BPEI Coated Diatomaceous Earth

Diatomaceous earth (DE) particles coupled with BPEI are created using asilane coupling agent. 100 g of DE along with 1000 mL isopropyl alcohol(IPA) and a magnetic stir bar is placed into an Erlenmeyer flask. 1 gm3-Isocyanatopropyltriethoxysilane is added to this solution and allowedto react for 2 hours. After 2 hours, 2 mL of BPEI is added and stirredfor an additional 5 hours before filtering and washing the particleswith IPA 2×'s and deionized water (DI water). The particles are thenfiltered and washed with a 0.12 M HCl solution in isopropanol (IPA) thendried.

Example 2 1% Chitosan CG800 Stock Solution

The chitosan stock solution is created by dispersing 10 g of chitosan(flakes) in 1000 mL of deionized water. To this solution is addedhydrochloric acid until a final pH of 5 is achieved by slowly andincrementally adding 12 M HCl while continuously monitoring the pH. Thissolution becomes a stock solution for chitosan deposition.

Example 3 Diatomaceous Earth—1% Chitosan Coating

10 g of diatomaceous earth is added to 100 mL deionized water with astir bar to create a 10% slurry. To this slurry is added 10 mL's of the1% chitosan stock solution of CG800. The slurry is allowed to stir for 1hour. Once the slurry becomes homogeneous the polymer is precipitatedout of solution by the slow addition of 0.1 N sodium hydroxide until thepH stabilizes above 7 and the chitosan precipitates onto the particlesof diatomaceous earth. The slurry is filtered and washed with a 0.05 MHCl solution in isopropanol (IPA) then dried.

Example 4 Particle Performance on Tailings Solution

Coated and uncoated diatomaceous earth particles were used inexperiments to test their ability to settle dispersed clay fines in anaqueous solution. The following procedure was used for each type ofparticle, and a control experiment was also performed where the particleaddition step was omitted.

One gram of particles was added to a centrifugation tube. Using asyringe, the centrifugation tube was then filled with 45 ml of tailingsolution containing dispersed clay. One more tube was filled with justthe tailings solution and no diatomaceous earth particles. The tube wasmanually shaken for 30 seconds and than placed on a flat countertop. Thetube was then observed for ten minutes allowing the clay fines to settleout.

Results:

No DE addition (control samples): Tailing solution showed no significantimprovement in cloudiness.

DE Coated with Chitosan: Tailing solution was significantly less cloudycompared to control samples.

DE Coated with BPEI: Tailing solution was significantly less cloudycompared to control samples.

DE Uncoated: Tailing solution showed no significant improvement incloudiness compared to control samples.

Example 5 Preparation of Polycation-Coated Washed Sea Sand

Washed sea sand is coated with each of the following polycations:chitosan, lupamin, BPEI, and PDAC. To perform the coating, an aqueoussolution was made of the candidate polycation at 0.01M concentration,based on its molecular weight. 50 g washed sea sand was then placed in a250 ml jar, to which was added 100 ml of the candidate polycationsolution. The jar was then sealed and rolled for three hours. Afterthis, the sand was isolated from the solution via vacuum filtration, andthe sand was washed to remove excess polymer. The coated sea sand wasthen measured for cation content by solution depletion of an anionic dye(FD&C Blue #1) which confirmed deposition and cationic nature of thepolymeric coating. The sea sand coated with the candidate polymer wasthen used as a tether-attached anchor particle in interaction with fineparticulate matter that was activated by treating it with an activatingagent.

Example 6 Use of Polymer-Coated Sea Sand to Remove Fine Particles fromSolution

In this Example, a 45 ml. dispersion of fine materials (7% solids) froman oil sands tailings stream is treated with an activating polymer(Magnafloc LT30, 70 ppm). The fines were mixed thoroughly with theactivating polymer. 10 gm of sea sand that had been coated with PDACaccording to the methods of Example 1 were added to the solutioncontaining the activated fines. This mixture is agitated and isimmediately poured through a stainless steel filter, size 70 mesh. Aftera brief period of dewatering, a mechanically stable solid is retrieved.The filtrate is also analyzed for total solids, and is found to have atotal solids content of less than 1%.

Control Example Use of Sea Sand without Polymer Coating to Remove FineParticles from Solution

In this Example, a 45 ml. dispersion of fine materials (7% solids) istreated with an activating polymer (Magnafloc LT30, 70 ppm). The fineswere mixed thoroughly with the activating polymer. 10 gm of uncoated seasand were added to the solution containing the activated fines. Thismixture is agitated and is immediately poured through a stainless steelfilter, size 70 mesh. The filtrate is analyzed for total solids, and isfound to have a total solids content of 2.6%.

EQUIVALENTS

While specific embodiments of the subject invention have been discussed,the above specification is illustrative and not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of this specification. Unless otherwise indicated, allnumbers expressing quantities of ingredients, reaction conditions, andso forth used in the specification and claims are to be understood asbeing modified in all instances by the term “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth herein areapproximations that can vary depending upon the desired propertiessought to be obtained by the present invention.

1. A method of removing particulate matter from a fluid, comprising:providing an activating material capable of being affixed to theparticulate matter wherein the activating material is an anionicpolymer; affixing the activating material to the particulate matter toform an activated particle; providing anchor particles and providing atethering material capable of being affixed to the anchor particles,wherein the tethering material is a cationic polymer and the anchorparticles larger than the particulate matter; and adding thetether-bearing anchor particle to the fluid that comprises the activatedparticle, wherein the tethering material attaches to the activatedparticle to form a removable complex in the fluid that comprises theparticulate matter; and removing the removable complex from the fluid,thereby removing the particulate matter from the fluid.
 2. The method ofclaim 1, wherein the removable complex is removed by filtration.
 3. Themethod of claim 1, wherein the removable complex is removed bycentrifugation.
 4. The method of claim 1, wherein the removable complexis removed by gravitational settling.
 5. The method of claim 1, whereinthe anchor particle comprises sand indigenous to the geographical areaof the method.
 6. The method of claim 1, wherein the tethering materialis selected from the group consisting of polyvinylamine, branchedpolyethylenimine and polydiallyldimethyl ammonium chloride.
 7. Themethod of claim 1, wherein the particulate matter comprises quartzand/or clay fines.
 8. The method of claim 1, wherein the particlescomprise oil sands.
 9. The method of claim 1, wherein the complex ismechanically stable.
 10. The method of claim 1, further comprising thestep of constructing a road or dyke with the complex.
 11. The method ofclaim 1, further comprising the step of reclaiming land with thecomplex.
 12. A method of removing particulate matter from a fluid,comprising adding an anionic polymer to the fluid, thereby coating theparticulate matter with the polymer; providing modified particlescomprising particles functionalized by attachment of at least one aminefunctional group wherein the particles larger than the particulatematter adding the modified particles to the fluid; and, dispersing themodified particles within the fluid so that they contact the coatedparticulate matter to form removable complexes in the fluid, andremoving the removable complexes from the fluid.
 13. The method of claim12, wherein the removable complexes are removed by filtration.
 14. Themethod of claim 12, wherein the removable complexes are removed bycentrifugation.
 15. The method of claim 12, wherein the removablecomplexes are removed by gravitational settling.
 16. The method of claim12, wherein the removable complexes are removed by skimming.
 17. Themethod of claim 12, wherein the fluid is a tailing solution.
 18. Themethod of claim 17 wherein the particulate matter comprises quartzand/or clay fines.
 19. The method of claim 12, wherein the particlescomprise oil sands.
 20. The method of claim 12, wherein the complex ismechanically stable.
 21. The method of claim 12, further comprising thestep of constructing a road or dyke with the complex.
 22. The method ofclaim 12, further comprising the step of reclaiming land with thecomplex.